The present invention comprises a pigment dispersant. More particularly, it comprises such a dispersant having an acrylic resin containing organic acid and strong-acid phosphorus-containing monomers.
Sulfur-and phosphorus-containing monomers, including 2-acrylamide-2-methylpropane sulfonic acid (AMPS), have been polymerized with acrylics and other monomers in various proportions for a variety of purposes, including for use in dispersing sediments in water. However, an optimum dispersant resin for use in water-based coating compositions has remained an elusive desideratum.
U.S. Pat. No. 4,450,013--Hirsch et al. (1984) teaches a pigment grinding or dispersing resin of, for instance, 40-90% by weight acrylic acid, 10-60% AMPS, and 0-10% acrylonitrile, or equivalent monomers. (Parts, percentages and proportions herein are by weight except where indicated otherwise).
U.S. Pat. No. 3,711,449--Brendley (1973) teaches interpolymers of 0.2-1.0% AMPS with other acrylates or methacrylates.
U.S. Pat. No. 3,898,037--Lange et al. (1975) teaches acrylamido-sulfonic acid polymers such as AMPS which may be copolymerized with other acrylics, and their use in corrosion inhibition.
U.S. Pat. No. 4,177,178--Das et al. (1979) teaches the use of AMPS copolymerized with other acrylics including long chain acrylics such as stearyl methacrylate, with a molecular weight of 15,000 to 100,000. These are said to be used to make thermosetting automotive topcoat paints.
U.S. Pat. No. 4,001,150--June et al. (1977) teaches the use of phosphoric or sulfonic esters, including AMPS, copolymerized with acrylics such as methacrylic acid, for use as an electroconductive resin.
U.S. Pat. No. 2,914,499--Sheetz (1959) teaches the use of various acrylic esters of sulfonic acid in emulsion polymerization.
U.S. Pat. No. 4,008,293--Maska et al. (1977) teaches the preparation of crosslinkable coating compositions containing, for instance, AMPS, as an internal crosslinking catalyst.
European Patent Publication 129,329--Farrar et al. (1984) teaches pigment dispersions using copolymers of acrylic acid with 1-50% AMPS having molecular weights in the range of 1,000 to 5,000, or up to 5700, with a low polydispersity.
European Patent Publication 58,865--Perrey et al. (1982) teaches pigment dispersants with 1-10% pigment, using various acrylic sulfonic acid polymers.
European Patent Publication 170,474--Backhouse (1986) teaches the use of phosphorus-containing compounds in water-based polymers to reducing gasing from metal pigments.